lua/ltablib.c at master · rubinus/lua · GitHub

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** $Id: ltablib.c $

** Library for Table Manipulation

** See Copyright Notice in lua.h

#define ltablib_c

#define LUA_LIB

#include "lprefix.h"

#include <limits.h>

#include <stddef.h>

#include <string.h>

#include "lua.h"

#include "lauxlib.h"

#include "lualib.h"

** Operations that an object must define to mimic a table

** (some functions only need some of them)

#define TAB_R 1 /* read */

#define TAB_W 2 /* write */

#define TAB_L 4 /* length */

#define TAB_RW (TAB_R | TAB_W) /* read/write */

#define aux_getn(L,n,w) (checktab(L, n, (w) | TAB_L), luaL_len(L, n))

static int checkfield (lua_State *L, const char *key, int n) {

lua_pushstring(L, key);

return (lua_rawget(L, -n) != LUA_TNIL);

}

** Check that 'arg' either is a table or can behave like one (that is,

** has a metatable with the required metamethods)

static void checktab (lua_State *L, int arg, int what) {

if (lua_type(L, arg) != LUA_TTABLE) { /* is it not a table? */

int n = 1; /* number of elements to pop */

if (lua_getmetatable(L, arg) && /* must have metatable */

(!(what & TAB_R) || checkfield(L, "__index", ++n)) &&

(!(what & TAB_W) || checkfield(L, "__newindex", ++n)) &&

(!(what & TAB_L) || checkfield(L, "__len", ++n))) {

lua_pop(L, n); /* pop metatable and tested metamethods */

}

else

luaL_checktype(L, arg, LUA_TTABLE); /* force an error */

}

static int tinsert (lua_State *L) {

lua_Integer pos; /* where to insert new element */

lua_Integer e = aux_getn(L, 1, TAB_RW);

e = luaL_intop(+, e, 1); /* first empty element */

switch (lua_gettop(L)) {

case 2: { /* called with only 2 arguments */

pos = e; /* insert new element at the end */

break;

}

case 3: {

lua_Integer i;

pos = luaL_checkinteger(L, 2); /* 2nd argument is the position */

/* check whether 'pos' is in [1, e] */

luaL_argcheck(L, (lua_Unsigned)pos - 1u < (lua_Unsigned)e, 2,

"position out of bounds");

for (i = e; i > pos; i--) { /* move up elements */

lua_geti(L, 1, i - 1);

lua_seti(L, 1, i); /* t[i] = t[i - 1] */

}

break;

}

default: {

return luaL_error(L, "wrong number of arguments to 'insert'");

}

lua_seti(L, 1, pos); /* t[pos] = v */

return 0;

}

static int tremove (lua_State *L) {

lua_Integer size = aux_getn(L, 1, TAB_RW);

lua_Integer pos = luaL_optinteger(L, 2, size);

if (pos != size) /* validate 'pos' if given */

/* check whether 'pos' is in [1, size + 1] */

luaL_argcheck(L, (lua_Unsigned)pos - 1u <= (lua_Unsigned)size, 1,

"position out of bounds");

lua_geti(L, 1, pos); /* result = t[pos] */

for ( ; pos < size; pos++) {

lua_geti(L, 1, pos + 1);

lua_seti(L, 1, pos); /* t[pos] = t[pos + 1] */

}

lua_pushnil(L);

lua_seti(L, 1, pos); /* remove entry t[pos] */

return 1;

}

** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever

** possible, copy in increasing order, which is better for rehashing.

** "possible" means destination after original range, or smaller

** than origin, or copying to another table.

static int tmove (lua_State *L) {

lua_Integer f = luaL_checkinteger(L, 2);

lua_Integer e = luaL_checkinteger(L, 3);

lua_Integer t = luaL_checkinteger(L, 4);

int tt = !lua_isnoneornil(L, 5) ? 5 : 1; /* destination table */

checktab(L, 1, TAB_R);

checktab(L, tt, TAB_W);

if (e >= f) { /* otherwise, nothing to move */

lua_Integer n, i;

luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3,

"too many elements to move");

n = e - f + 1; /* number of elements to move */

luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4,

"destination wrap around");

if (t > e || t <= f || (tt != 1 && !lua_compare(L, 1, tt, LUA_OPEQ))) {

for (i = 0; i < n; i++) {

lua_geti(L, 1, f + i);

lua_seti(L, tt, t + i);

}

else {

for (i = n - 1; i >= 0; i--) {

lua_geti(L, 1, f + i);

lua_seti(L, tt, t + i);

}

lua_pushvalue(L, tt); /* return destination table */

return 1;

}

static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) {

lua_geti(L, 1, i);

if (l_unlikely(!lua_isstring(L, -1)))

luaL_error(L, "invalid value (%s) at index %I in table for 'concat'",

luaL_typename(L, -1), (LUAI_UACINT)i);

luaL_addvalue(b);

}

static int tconcat (lua_State *L) {

luaL_Buffer b;

lua_Integer last = aux_getn(L, 1, TAB_R);

size_t lsep;

const char *sep = luaL_optlstring(L, 2, "", &lsep);

lua_Integer i = luaL_optinteger(L, 3, 1);

last = luaL_optinteger(L, 4, last);

luaL_buffinit(L, &b);

for (; i < last; i++) {

addfield(L, &b, i);

luaL_addlstring(&b, sep, lsep);

}

if (i == last) /* add last value (if interval was not empty) */

addfield(L, &b, i);

luaL_pushresult(&b);

return 1;

}

** {======================================================

** Pack/unpack

** =======================================================

static int tpack (lua_State *L) {

int i;

int n = lua_gettop(L); /* number of elements to pack */

lua_createtable(L, n, 1); /* create result table */

lua_insert(L, 1); /* put it at index 1 */

for (i = n; i >= 1; i--) /* assign elements */

lua_seti(L, 1, i);

lua_pushinteger(L, n);

lua_setfield(L, 1, "n"); /* t.n = number of elements */

return 1; /* return table */

}

static int tunpack (lua_State *L) {

lua_Unsigned n;

lua_Integer i = luaL_optinteger(L, 2, 1);

lua_Integer e = luaL_opt(L, luaL_checkinteger, 3, luaL_len(L, 1));

if (i > e) return 0; /* empty range */

n = (lua_Unsigned)e - i; /* number of elements minus 1 (avoid overflows) */

if (l_unlikely(n >= (unsigned int)INT_MAX ||

!lua_checkstack(L, (int)(++n))))

return luaL_error(L, "too many results to unpack");

for (; i < e; i++) { /* push arg[i..e - 1] (to avoid overflows) */

lua_geti(L, 1, i);

}

lua_geti(L, 1, e); /* push last element */

return (int)n;

}

/* }====================================================== */

** {======================================================

** Quicksort

** (based on 'Algorithms in MODULA-3', Robert Sedgewick;

** Addison-Wesley, 1993.)

** =======================================================

/* type for array indices */

typedef unsigned int IdxT;

** Produce a "random" 'unsigned int' to randomize pivot choice. This

** macro is used only when 'sort' detects a big imbalance in the result

** of a partition. (If you don't want/need this "randomness", ~0 is a

** good choice.)

#if !defined(l_randomizePivot) /* { */

#include <time.h>

/* size of 'e' measured in number of 'unsigned int's */

#define sof(e) (sizeof(e) / sizeof(unsigned int))

** Use 'time' and 'clock' as sources of "randomness". Because we don't

** know the types 'clock_t' and 'time_t', we cannot cast them to

** anything without risking overflows. A safe way to use their values

** is to copy them to an array of a known type and use the array values.

static unsigned int l_randomizePivot (void) {

clock_t c = clock();

time_t t = time(NULL);

unsigned int buff[sof(c) + sof(t)];

unsigned int i, rnd = 0;

memcpy(buff, &c, sof(c) * sizeof(unsigned int));

memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int));

for (i = 0; i < sof(buff); i++)

rnd += buff[i];

return rnd;

}

#endif /* } */

/* arrays larger than 'RANLIMIT' may use randomized pivots */

#define RANLIMIT 100u

static void set2 (lua_State *L, IdxT i, IdxT j) {

lua_seti(L, 1, i);

lua_seti(L, 1, j);

}

** Return true iff value at stack index 'a' is less than the value at

** index 'b' (according to the order of the sort).

static int sort_comp (lua_State *L, int a, int b) {

if (lua_isnil(L, 2)) /* no function? */

return lua_compare(L, a, b, LUA_OPLT); /* a < b */

else { /* function */

int res;

lua_pushvalue(L, 2); /* push function */

lua_pushvalue(L, a-1); /* -1 to compensate function */

lua_pushvalue(L, b-2); /* -2 to compensate function and 'a' */

lua_call(L, 2, 1); /* call function */

res = lua_toboolean(L, -1); /* get result */

lua_pop(L, 1); /* pop result */

return res;

}

** Does the partition: Pivot P is at the top of the stack.

** precondition: a[lo] <= P == a[up-1] <= a[up],

** so it only needs to do the partition from lo + 1 to up - 2.

** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up]

** returns 'i'.

static IdxT partition (lua_State *L, IdxT lo, IdxT up) {

IdxT i = lo; /* will be incremented before first use */

IdxT j = up - 1; /* will be decremented before first use */

/* loop invariant: a[lo .. i] <= P <= a[j .. up] */

for (;;) {

/* next loop: repeat ++i while a[i] < P */

while ((void)lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) {

if (l_unlikely(i == up - 1)) /* a[i] < P but a[up - 1] == P ?? */

luaL_error(L, "invalid order function for sorting");

lua_pop(L, 1); /* remove a[i] */

}

/* after the loop, a[i] >= P and a[lo .. i - 1] < P */

/* next loop: repeat --j while P < a[j] */

while ((void)lua_geti(L, 1, --j), sort_comp(L, -3, -1)) {

if (l_unlikely(j < i)) /* j < i but a[j] > P ?? */

luaL_error(L, "invalid order function for sorting");

lua_pop(L, 1); /* remove a[j] */

}

/* after the loop, a[j] <= P and a[j + 1 .. up] >= P */

if (j < i) { /* no elements out of place? */

/* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */

lua_pop(L, 1); /* pop a[j] */

/* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */

set2(L, up - 1, i);

return i;

}

/* otherwise, swap a[i] - a[j] to restore invariant and repeat */

set2(L, i, j);

}

** Choose an element in the middle (2nd-3th quarters) of [lo,up]

** "randomized" by 'rnd'

static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {

IdxT r4 = (up - lo) / 4; /* range/4 */

IdxT p = rnd % (r4 * 2) + (lo + r4);

lua_assert(lo + r4 <= p && p <= up - r4);

return p;

}

** Quicksort algorithm (recursive function)

static void auxsort (lua_State *L, IdxT lo, IdxT up,

unsigned int rnd) {

while (lo < up) { /* loop for tail recursion */

IdxT p; /* Pivot index */

IdxT n; /* to be used later */

/* sort elements 'lo', 'p', and 'up' */

lua_geti(L, 1, lo);

lua_geti(L, 1, up);

if (sort_comp(L, -1, -2)) /* a[up] < a[lo]? */

set2(L, lo, up); /* swap a[lo] - a[up] */

else

lua_pop(L, 2); /* remove both values */

if (up - lo == 1) /* only 2 elements? */

return; /* already sorted */

if (up - lo < RANLIMIT || rnd == 0) /* small interval or no randomize? */

p = (lo + up)/2; /* middle element is a good pivot */

else /* for larger intervals, it is worth a random pivot */

p = choosePivot(lo, up, rnd);

lua_geti(L, 1, p);

lua_geti(L, 1, lo);

if (sort_comp(L, -2, -1)) /* a[p] < a[lo]? */

set2(L, p, lo); /* swap a[p] - a[lo] */

else {

lua_pop(L, 1); /* remove a[lo] */

lua_geti(L, 1, up);

if (sort_comp(L, -1, -2)) /* a[up] < a[p]? */

set2(L, p, up); /* swap a[up] - a[p] */

else

lua_pop(L, 2);

}

if (up - lo == 2) /* only 3 elements? */

return; /* already sorted */

lua_geti(L, 1, p); /* get middle element (Pivot) */

lua_pushvalue(L, -1); /* push Pivot */

lua_geti(L, 1, up - 1); /* push a[up - 1] */

set2(L, p, up - 1); /* swap Pivot (a[p]) with a[up - 1] */

p = partition(L, lo, up);

/* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */

if (p - lo < up - p) { /* lower interval is smaller? */

auxsort(L, lo, p - 1, rnd); /* call recursively for lower interval */

n = p - lo; /* size of smaller interval */

lo = p + 1; /* tail call for [p + 1 .. up] (upper interval) */

}

else {

auxsort(L, p + 1, up, rnd); /* call recursively for upper interval */

n = up - p; /* size of smaller interval */

up = p - 1; /* tail call for [lo .. p - 1] (lower interval) */

}

if ((up - lo) / 128 > n) /* partition too imbalanced? */

rnd = l_randomizePivot(); /* try a new randomization */

} /* tail call auxsort(L, lo, up, rnd) */

}

static int sort (lua_State *L) {

lua_Integer n = aux_getn(L, 1, TAB_RW);

if (n > 1) { /* non-trivial interval? */

luaL_argcheck(L, n < INT_MAX, 1, "array too big");

if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */

luaL_checktype(L, 2, LUA_TFUNCTION); /* must be a function */

lua_settop(L, 2); /* make sure there are two arguments */

auxsort(L, 1, (IdxT)n, 0);

}

return 0;

}

/* }====================================================== */

static const luaL_Reg tab_funcs[] = {

{"concat", tconcat},

{"insert", tinsert},

{"pack", tpack},

{"unpack", tunpack},

{"remove", tremove},

{"move", tmove},

{"sort", sort},

{NULL, NULL}

};

LUAMOD_API int luaopen_table (lua_State *L) {

luaL_newlib(L, tab_funcs);

return 1;

}

lua/ltablib.c at master · rubinus/lua · GitHub

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